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THE CAMERA IN WAR TIME

MARVELLOUS ACHIEVEMENTS

LONG DISTANCE SPYING

(By P. 'Stockbridge, in the "New York Herald")

Very early in tlio war tho Allies discovered that the 'best results from tlio use of tho airplane for observation could bo attained only <by meajis of photogiaphy; it was not long before the'photographic recording of the enemy's positions and movements became the principal object of military aviation. Even bombing was not at any, time, regarded ns anything but ti secondary use of the airplane, while the lighting plane 3 owned their existence solely to the necessity of protecting the observation planes from attack, and-of 'driving-off tho enemy observers.

Here, as in almost ovary other , field of applied science, Germany had a dis"tinct advantage at the beginning of the -war.' Germany had developed photogra-. phic, apparatus. espeoially for airplane u's6; the 'aerial observers of v the, Allies bail to compete -in' the beginning with short-range, portable hand cameras. Germany had trained hundreds'of men in ,the new art of reading aerial photographs; the Allies had to' learn it all, after they got<intothe war. But here, as in other fields, Gfinnany made the mistake "of.'.supposing. .that .because her enemies had not.prepafed themselves in these directions it was because they were unable to do.\these things; when the Allies took up seriously the development of aerial photography, it was carried so much, farther and developed to' su'oh' a Tiigher pitch' of perfection than anything Germany had dreamed of, that no Prussian oanloufloge'-could hide the Hun's movements from'us in the later ■ days of the weir, hardly could .even clouds prevent the photographing of every detail of, the' enemy's positions while our observers remained themselvei unseen from the ground! Beyond a doubt Gormany relied upon.' her practical monopoly of the optical ' glass industry to keep the nations opposing her in the field from'being equipped with high-rgrade' lonses .for photography, for rangefinders and ' for field-glasses, necessary to war on any large 'scale. I For, nearly a quarter of .a century the manufacture of .the .best, grades of gloss for these had centred at Jena, Prussia; many grades essential to the . manufacture of modern' high-speed , lenses'-were not made anywhere else in the-world; The .University of Jena had established great laboratories for research ,in glass., making and, lens development, and the Gorman Government hadsubsidifitckl extensive manufacturing plants, which made the photograbhio and other lenses for the whole world. Early ' Problems. < By the end of 1914 the importation of optical glass'had become difficult and uncertain. One' American firm had be- . gun some experiments, others established laboratories, 1 and the Bureau of 'Standards of. the United States Department of. . 'Commerce set, some of its scientists ': to ■work on the problem. Glass that answered one important purpose of Jena glass,- that of material for test tubes and other laboratory apparatus; was soon developed, and has proved, so much better : than anything Germany ever made that there is no possible chancei of any_ future German competition. Great Britain succeeded in- getting' l ' good production of some grades of, glass that gave acceptable results when,ground into camera lenses; but by 1917,. .when. Jhe United States entered the war, the optical glass situation bad become critical.' Such as France' said Great Britain were able to produce •was inadequate for even their needs. . Wonderful.'as -ire the GermanUenses, composed of glass;of .three or four, dif: ferent' qualities and consistencies, to give the greatest possible light gathering power, they, have seldom - been produced in the larger sizes without flaws in the . glass, which, the German herr professors solemnly, assured us, did not- really.in-, teh'ere with the excellence-of the lenses. ' We ar'e : making the largest lenses without 'flaws, and find they work faster than • those with flaws'in them, strange'may seem—to the Germans. ' -Arid' neyer again will-the rest of the world be dependent upon Germany for lenses;' that chainhas - been snapped for ever!

Learning how to make tenses was only one step, however,', in the application of scientific knowledge and . methods ot photography that was such an important development of the war. ; .'ln the begin, ning of the war photographic observers could fly at low altitudes; before hostilities ceased "it was a foolhardy photographer who tried to take pictures from less than a mile high, while two or three miles was a much safer altitude. This made a hand oamera useless, and huge devices permanently attaohed to the aeroplane, equipped with lenses larger than had been used for such purposes, had to be dovised. The ordinary view camerahas a focal strength, or distance between •the centre lens and ' th-j olate, of from seven to ten or twelve inches,, lenses ordinarily in use haying a longer '.focal strength are small, having a working diameter of from one-eighth to - one-fifteenth •of ' the ' foqal strength, requiring long exposures. But before the Hrmistice was signed wo had made in this country perfect, lenses. having a focal, length - of fifty inches and liavihg a diameter of ten inches—what • photographers term" "an ; aperture of F,5!" - , . ~

. • Even Footprints Were Recorded. i . Equipped with a camera of this enor-'< moussize, the. lens protruding through : the bottom of the fuselage of his airplane the aerial observer can fly at a, •height of three miles or more, and with an exposure of r. five-hundredth of a seoond, or even less, make a picture'of the ground beneath so full of detail that the trained experts at the laboratory behind his own-line can detect even the footprints that show where the men had marched over the damp earth the night before. From this mechanical eye nothing is 'hidden, even objects that the air- • ■ man himself cannot see are brought out in full detail by these huge lenses, while the colour, values, that make it possible " to differentiate even between two varieties of evergreen trees by a study of photographs taken from the sky, are accentuated 'by two other reraarkablo photographic developments of the war, the pan-chromatic plate and the new ray filter. Herotoforo tho combination of high-speed photography. with accurate colour values 'has been regarded.as impossible; it is literally true that with the new "emulsion," as the chemical coating of the negative plate is called, photographs can made under light conditions 'heretofore impossible, at speeds as great as 'were formerly possible in full sunlight, and instead of being solid blacks and whites, as is usually the case with under-exposea pictures, will contain a wide range of gradations that make the distinction between objects of the same,shape, but' of dilforent materials'so easy as to be almost miraculous;'. Proper rendition of colour value is aided by ray filtei'3. One of these de-/ vicis, in addition, onables the aviator to perform the marvellous trick of photographing through a cloud that completely obscures his vision of the earth and getting a picture that shows the details of tho surface. Through the hazo that is hardly thick enough to bo called cloud, but which makes ordinary long-distance vision • impossible, such photographs are as,.easy as though the atmosphere were perfectly clear, through thin clouds, almost, if not quite, thick enough to hide the airmen from observation on the ground, photographs have also been made. ■ !

Rapid Developing. Developing negatives and , mating prints from them was formerly ?. comparatively slow process; few photographers, even tho fast-working professionals of tho newspaper staffs, knew any tricks that-would speed tho process down to an elapsed time of much less than 20 minutes. Through purely scientific'methods, devised "by exports who had never had practical expcrienco in high-speed photographic work, but who were completely equipped chemists, ways havo been found to develop the negative and produce net only one but a number of fin ished prints in less than ten minutesj a quarter of an honr after the aerial'observer has landed expert photograph, readers we transferring to maps the new data which his photographs reveal; five minutes later the .commanding officers of 'the entire. 6ector know the enemy's latest movements miles behind the lines. The development of the aerial camera

into a magazine carrying fifty plates was followed by an automatic plate-changing device that made the observer's task the mere pressing of a button. On America's entry into the war the adaptation of the flexible photographic film to tho aorial camera began. The film is Amorica's most important and distinctive contribution to the art of photography. It had been neglected by the professional photographer because of the difficulty in 'making it lie flat and the way it has of fogging beciiuso of frictional electrical discharges as it is rolled from one spool to another in, very cold weather—and it is always very cold weather at three miles up in the air! Again science overcame obstacles. Films in rolls twenty inches wide and containing enough for one hundred exposures of fifteen by twenty inches are made to lie flat in the latest American aerial camera by passing the part <)f the film to be exposed under a plate pierced with hundreds of tiny holes, through which nir is exhausted, thus holding the film flat against the plate; the suction is accomplished by means of a venturi tube attached to the frame of the machine, tho wind caused by. the machine's motion providing sufficient pressure. This simple and efficacious schemo was the invention of one college professor; another worked out the scheme for pre venting electrical- fogging by covering every metal part over whioli, the film passes with cloth, the thread and meshes of which are filled with graphite, reducing friction to practically nothing. _ This same camera is entirely automatic in its notion. The observer needs only to pull a 'trigger, and so long as he holds it down the. camera will take one photograph after another at a rate dependent upon - the speed at which lie is flying. Tnese photographs, placed edge to edge, o;. with a slight overlap, give a perfect map of .--the terrain traversed. - Perfect Map-Making, With the combination of powerful lenses that take in every detail at high speed, ray filters and panchromatic plates tinit distinguish and record colour values, and the automatic device that shifts the film at regular intervals, it iB now possible to mako a map of any part 6f the vorld in a few minutes that would have taken surveyors years to make. There are,sections of the United States, many of them huge areas like the desert and mountain "oonntry of the South-west that have never been explored or- surveyed. It is how possible to map them easily and with mathematical, accuracy, only a moderate amount of triangulation to determine relative elevations being necessary. Where the, country is level «jr' with few elevations, there is practically nothing left for old-fashioned surveying • methods to accomplish. The Army Aviation Corps recently aegan the work of mapping the State of Oklahoma photographically,- centring the work at Fort Sill. The most remarkable map of this sort that has been made, however, isthe one of the city of .Washington, This map, composed of 300 \flfotographs placed together, was made in two, and a' half hours; it has been calculated that a corps of 10 surveyors would take five years to do the same piece of work, and the results would not be. so accurate!, Every bush in tho parks is shown, the shape of every building, every, klley aiid thoroughfare, while the black shadow of the Washington Monument, with its known 555 feet of height, gives a key from which every other elevation can ba calculated by the length of the photographed shadow. | Herb.is a contribution to peacetime activities and interests of vast importance;, accurate, detailed maps of cities, such as cttn.be made in this manner at small expense, now cost hundreds of dollars a copy; millions of Government money may be saved by using this method to map the public domain; its usefulness iu the oil nelds, in surveying timber lands, and .in a thousand w&ys that need no further elaboration, is obvious. /For' the more' accurate determination of elevations the steroscopic principle is applied,to. aerial' photography. Everyone, is familiar with, the stereoscope, the device that enables one to look at a photograph—or, rather, two photographs —through simple prism lenses, and, instead of seeing the picture, in a flat plane, get the effect of viewing the actual object, which stands.out in relief. This is' accomplished' .by taking' two photographs' .simultaneously ■ with the -two lenses-at the distance from each other of : the ''average 'huitfah eye, about' three inches; by means'of the prisms, the'two pictures are'seen -as one and the effect of depth results. In aerial stereoscopic photography the two - pictures may be taken a couple of miles apart; the airman sets his at an angle and makes an oblique' picture as he approaches his object;, then he turns and photographs; it at the_ same angle from the opposite;side.. When the two pictures' are viewed' together the precise height of every elevation and the depth of every depression are determined accurately. Entirely apart from its aerial phases, however, photography, both injhe proof that has been afforded of the applicability of many scientific methods heretofore untried and undeveloped and in the training .of thousands of photographers in faster and better ways of doing their work,' ha 3 received a definite dividend from the war.

Permanent link to this item
Hononga pūmau ki tēnei tūemi

https://paperspast.natlib.govt.nz/newspapers/DOM19190507.2.43

Bibliographic details
Ngā taipitopito pukapuka

Dominion, Volume 12, Issue 190, 7 May 1919, Page 7

Word count
Tapeke kupu
2,196

THE CAMERA IN WAR TIME Dominion, Volume 12, Issue 190, 7 May 1919, Page 7

THE CAMERA IN WAR TIME Dominion, Volume 12, Issue 190, 7 May 1919, Page 7

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